Applying multi-criteria decision analysis to select WSUD and LID technologies

Water Sensitive Urban Design (WSUD) and Low Impact Development (LID) principles were investigated in Dhaka's drainage network using ‘Regime in Balance’ strategy for Average Recurrence Interval (ARI), Y = 100 years. Three feasible alternatives, such as, leaky-well, soak-away and infiltration trench were identified and designed to improve Dhaka's present unsatisfactory stormwater drainage system into one which is sustainable. For selecting the best one, we applied a multi-criteria decision analysis approach and chose the Analytic Hierarchy Process (AHP) model. Eleven criteria under three categories (technical, economic and social) were considered to quantify relative priorities of alternatives. Pair-wise comparisons of alternatives were performed against each criterion and ranked using a scale from 0 to 9. During the process of applying AHP model, consistency of ranking was thoroughly checked and a reasonable level of inconsistency was accepted due to the nature of human judgement. After the analysis, it was found that leaky-well (percentage priority 43%) followed by soak-away (38%) was the most appropriate technology for improving urban stormwater management system in Dhaka, Bangladesh. The proposed model can also be used in better selecting WSUD and LID technologies in other geographic locations.